Adaptive bit rate media streaming may be used to deliver media content to a device. Adaptive bit rate media streaming may rely on content encoded at multiple encoding bit rates (quality levels), each content item stored in a separate file and segmented into fixed-duration chunks. Streaming services may utilize chunks that are about 2 seconds in duration for streaming via the internet and may utilize chunks that are about 10 seconds in duration for streaming via mobile communications networks. The device that is to receive streaming media content decides which chunk to request and requests the chunk at a particular quality level based on an estimate of network condition. The estimate of network conditions may be based on historical information for the device (e.g., download rate for the device, download rate for packets of a prior set of packets for a chunk, number of requests for replacement packets to replace corrupt packets in received chunks, etc.). Once the device requests a particular chunk, the device will download the particular chunk, process the particular chunk, and send output to an output device (e.g., a display device, an audio system, or both).